One interesting observation is the finding that HDAC6 expression is increased by 52% in the Alzheimer’s disease cortex and by 91% in the Alzheimer’s disease hippocampus, when compared with young normal brains [46], as tau pathology progresses from entorhinal to hippocampal to neocortical regions [47]. The gene discussed is HDAC6; the disease is early-onset autosomal dominant Alzheimer disease.